This application relates to allergen-barrier covers for bedding and other articles which harbor dust mites and other household allergens. It is now generally accepted that dust mites, dust mite feces and other microscopic allergens found in bedding and upholstered furniture are a significant cause of many asthmatic and allergic reactions in the home. See, Walshaw et al., Quarterly J. Med. 58: 199-215 (1986). To reduce exposure to such allergens, various suggestions have been made for covering bedding in covers which act as a barrier to the passage of allergens.
U.S. Pat. No. 5,050,256 discloses an allergen-barrier bedding cover made from a coated fabric. The fabric is said to have a pore size of less than 10 microns to prevent the passage of dust mites. The fabric is sewn to form the cover and the seams are sealed with an additional coating of polyurethane.
U.S. Pat. No. 5,321,861 discloses a protective cover for upholstered or padded articles, made from a microporous ultrafilter material having still smaller pores of less than 0.5 microns. To eliminate possible leakage of allergens through the seams or zipper closure, these covers are constructed using high frequency welding, and the zipper is covered by an adhesive tape. The use of an adhesive tape over the zipper is cumbersome for real usage, particularly in a bedding cover which may need to be removed and washed frequently. Thus, it would be desirable to have a cover which acted as a highly effective allergen barrier while at the same time providing easy removal for washing as necessary. It is an object of the present invention to provide covers which meet this need.